An 18-year-old woman comes to the office as she has not had a menstrual period for the last 3 months. Menarche was at age 12, and her menstrual cycles were previously every 28 days, with 3-4 days of moderate bleeding. The patient has had no changes in appetite, headaches, vision or voice changes, or nipple discharge. She has no chronic medical conditions or previous surgeries. Family history is noncontributory. The patient is a gymnast and has increased her training to 4 hours a day to prepare for a national competition. She has never been sexually active. The patient takes ibuprofen occasionally after practices and has no known allergies. Temperature is 37.2 C (99 F), blood pressure is 100/60 mm Hg, pulse is 60/min, and respirations are 12/min. BMI is 18 kg/m². Physical examination shows well-defined musculature. Hair is present above the upper lip and on the forearms. The breasts are atrophic, with no nipple discharge. The abdomen is soft and nontender and has no palpable masses. Pelvic examination indicates a sexual maturity rating at stage 5. Bimanual examination reveals a small, anteverted, mobile uterus and small ovaries. Which of the following is the most likely diagnosis in this patient?

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Explanation: 11ec2b69_c13f_fff3_8f63_b99cd7cb54bc_MD0005_00 Patients with functional hypothalamic amenorrhea (FHA) typically have amenorrhea, a low BMI, and findings of estrogen deficiency (breast atrophy). Additional features include anovulatory infertility and vaginal atrophy with dyspareunia. Female athletes are particularly susceptible to FHA due to a relative caloric deficiency associated with strenuous physical activity and high energy expenditure; other causes include stress and anorexia nervosa. The relative caloric deficiency results in decreased levels of GnRH resulting in decreased LH and FSH levels, suppressed ovarian function, and low estrogen levels. Patients with FHA also have an increased risk of bone fracture due to increased bone resorption from inadequate caloric intake. Therefore, a bone mineral density measurement (eg, DXA) is indicated in these patients. This constellation of symptoms (eg, oligomenorrhea or amenorrhea, relative caloric deficiency, decreased bone mineral density) constitutes the athlete triad that characterizes FHA. Treatment includes increased caloric intake, calcium and vitamin D supplementation, and estrogen for bone loss prevention. (Choice A) Exogenous growth hormone (GH) is used as a performance enhancer in athletes to increase lean body mass and decrease body fat. This patient has the GH symptoms of well-defined musculature and low body fat. However, she also has amenorrhea; exogenous GH use is not associated with menstrual irregularities. In addition, patients using exogenous GH typically have associated hypertension and fluid retention (eg, edema, carpal tunnel syndrome), which are not seen in this patient. (Choice C) Nonclassic congenital adrenal hyperplasia typically presents with oligomenorrhea, acne, hirsutism, and clitoromegaly. There is no association with hypoestrogenism or a low BMI. (Choice D) Polycystic ovary syndrome can present with amenorrhea and hirsutism (eg, hair on upper lip). However, patients are typically obese, have features of estrogen excess (eg, breast tenderness) rather than deficiency, and have bilaterally enlarged ovaries on examination. (Choice E) Primary ovarian insufficiency, ovarian failure prior to age 40, is typically associated with concomitant autoimmune disease, Turner syndrome, or previous chemoradiation. Patients have oligomenorrhea or amenorrhea and hypoestrogenism, but there is no association with exercise. Laboratory evaluation shows elevated FSH and low estradiol levels. Educational objective: Functional hypothalamic amenorrhea presents with amenorrhea, hypoestrogenism, and a low BMI. Female athletes with this condition are at risk for decreased bone mineral density and fracture. The combination of bone loss, amenorrhea or oligomenorrhea, and decreased caloric availability constitutes the athlete triad. References: The female athlete triad. (http://www.ncbi.nlm.nih.gov/pubmed/27432852)

An 18-Year-Old Woman Comes to the Office as She Has